> restart;

> x:=r*cos(t);

> y:=r*sin(t);

> z:=sin(2*t);

> a:=plot3d([x,y,z],r=0..1,t=0..2*Pi,scaling=constrained,grid=[10,50]):

> a;

> with(plottools):

> vrml(a,"c:/042/12/12-11.wrl",background_color=white);

>